1 Field of the Invention
This invention relates to a plastic optical fiber end face treatment method and a treatment device, and more particularly relates to a treatment method and a treatment device that are suitable for forming a shape of a lens face on the end face of a plastic optical fiber.
2 Description of the Related Art
Conventionally, when an end face of an end of a plastic optical fiber is treated, the end of the plastic optical fiber is brought close to a high temperature source and the end is treated. For example, as shown in FIG. 9, a method in which using an end face treatment device for treating an end face 53 of a plastic optical fiber 50 provided with a chuck 60 for fixing an plastic optical fiber having a jacket with an exposed core end face 51a, a transfer face 62a at its end, and a metal mold 62 that is heated by means of a heater 61, a plastic optical fiber end 53 is held with the chuck 60 and moved toward the mold 62, the heated mold 62 is pressed against the core end face 51a of the plastic optical fiber end 53, the core end face 51a is softened and finished in a mirror-surface fashion, and the core end face is formed in a predetermined shape such as lens form or the like has been used.
Herein, generally as shown in FIG. 10, a plastic optical fiber 50 comprises a core 51 consisting of high purity polymethacrylate resin (PMMA) disposed at the center, a clad 52 consisting of special fluororesin that covers peripheral surface of the core 51, and a jacket (cover) that covers the peripheral surface of the clad 52. A light that enters from the one core end face of the core 51 emitted from a light source 70 is totally reflected on the boundary between the core 51 and clad 52, and comes out from the other core end face.
In the case of the conventional end face treatment method for treating a plastic optical fiber end 53, a softened core 51 expands in the direction of the core side face 51b because the core end face is heated and pressed against the mold 62 simultaneously, the expansion is a problem.
To avoid the above-mentioned problem, it is required that a member to be mounted is mounted so as to avoid the expansion portion of the core side face 51b when the plastic optical fiber end 53 is inserted into the connecting parts such as light branch and coupler.
In particular, in the case that a plastic optical fiber end 53 is inserted into a thin hole formed at the tip of a ferrule by use of the connection member such as ferrule (inner ring) not shown in the drawing, it is required that not only the core end face 51a but also the expanded portion of the core 51 is projected from the ferrule end face, the accurate positioning of the plastic optical fiber end 53 is difficult, and it is a problem.
It is the object of the present invention to provide a treatment method and a treatment device in which the expanded portion is not formed on the core side face when a plastic optical fiber end is softened and fused, and the end face of the plastic optical fiber end is finished in a mirror-surface fashion in the form of a predetermined shape.
In the first solving means to solve at least one of the above-mentioned problems, the core end face of a plastic optical fiber end is pressed on a mold that is heated to a certain temperature to soften and fuse the core end face and to transfer the transfer face of the mold on the core end face.
The second solving means comprises a step for pressing the core end face of a plastic optical fiber end on the transfer face of a heated mold, a step for separating the core end face from the mold and cooling the core end face naturally, and a step in which pressing/separating between the core end face and the transfer face of the mold is repeated intermittently to deform the shape of the core end face gradually and to transfer the transfer face of the mold.
In the third solving means, the core end face is formed in the lens face shape.
In the fourth solving means, a step in which the cover of the plastic optical fiber end is removed to expose the core end face is provided.
In the fifth solving means, a step in which the clad of the core end face of the plastic optical fiber end is removed is provided.
The sixth solving means is provided with a chuck member for fixing the plastic optical fiber end, a guide member for guiding the core end face of the plastic optical fiber end, a mold having a transfer face for treating the core end face in the form of a predetermined shape, a heating unit for heating the mold to a certain temperature, and a moving unit for moving the core end face of the plastic optical fiber end and the transfer face of the mold to the position where both are pressed each other and separated, wherein the plastic optical fiber end is fixed by means of the chuck member and the guide member, and the mold is heated by means of the heating unit, the moving unit is reciprocated repeatedly to thereby transfer the transfer face of the mold on the core end face gradually.